پیامدهای تبدیل جنگل‏های زاگرس به دیمزار بر کیفیت خاک در حوزه مرک استان کرمانشاه

The quantity and quality of Zagros Forests (west Iran) are declining through improper management and land-use practices negatively affecting life in the regional scale. The objective of this research was explored the change in soil quality through conversion of forest to rain-fed practices which was conducted in the Gazaf-e-olya village in the Merek watershed, Kermanshah, Iran. Thirty five soil samples were collected from surface soil layers and subjected to soil physicochemical analysis. The data also were analyzed both classical and semivariance using SAS software. The results showed that there was no significant difference for soil particles distributions (sand, silt and clay) in the forest and rain-fed areas. The respective level of bulk density (BD) in the forest and rain-fed was 1.26 and 1.32 gr^-1cm^-3, indicating significant difference (p<0.05%) between them. Soil aggregate stability (SA) value in the forest and rain-fed was 63.62 and 52.65 %, respectively. The positive significant differences were found for BD and SA in the forest as a good physical quality. There were no significant differences for pH, Na_exch., EC and P,  with moderate spatial variability, while other soil chemical characteristics including SOC, N, K, CEC have significant higher values (p<0.05%) in the forest compared to rain-fed area. There is concluded that land-use alteration, especially conversion of forest to rain-fed areas contributes to soil depletion and sever environmental problems and global warming.